Range queries are a very common task in SQL: selecting dates, numbers, or even text values that fall within some specified range. For instance: all loan applications for the month of March, or all sales transactions between $50 and $500. SQL developers are generally adept at writing such queries and indexing them to ensure they perform well.
But when the requirements are changed slightly — to compare two ranges of values to find where they overlap — it’s suddenly a whole new ballgame. These so-called “overlap queries” are trickier than they appear.
Overlap Queries
The most common overlap queries involve